Handedness of healthy elderly and patients with Alzheimer's disease

Abstract

Purpose/Aim of the study: Research has suggested decreasing proportions of non-right handers in older age groups and reduced incidence of non-right handedness among individuals with Alzheimer's disease (AD). We hypothesized that healthy elderly individuals would have a higher proportion of non-right handers than individuals with AD and that the proportion of non-right handers would decrease with increasing age. Further, we investigated whether the proportions of non-right handers differed between those with early and late onset of AD.Materials and Methods: Two-hundred and fifty-six healthy elderly and 182 individuals with AD served as participants. Hand dominance was recorded based on side of writing during testing and self-report. We analyzed proportions of right handers and non-right handers for three age ranges (≤ 69, 70 - 79, and ≥ 80 years). A second analysis focused on the proportions of right and non-right handers among patients with AD classified as either early or late disease onset.Results: Handedness proportions did not differ between the controls and ADs. For AD but not for controls, there was a trend towards reduced proportions of non-right handers with increasing age. Early onset AD was associated with a larger proportion of non-right handers compared to those with late onset AD.Conclusions: Results did not support a trend of decreasing non-right handedness with increasing age in controls, but did provide support for such a trend in individuals with AD. The results provided support for the hypothesis of increased incidence of non-right handedness in early onset vs. late onset AD.

Keywords: Alzheimer’s disease; early onset; handedness; healthy elderly; late onset.